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Abstract: FR-PO683

Dysregulation of Podocyte Clock-Controlled Autophagy in a Neonatal Hyperoxia Model

Session Information

  • Pediatric Nephrology - 1
    October 25, 2024 | Location: Exhibit Hall, Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1900 Pediatric Nephrology

Authors

  • Duara, Joanne, University of Miami Batchelor Children's Research Institute, Miami, Florida, United States
  • Njeim, Rachel, Peggy and Harold Katz Family Drug Discovery Center, Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida, United States
  • Pressly, Jeffrey D., Peggy and Harold Katz Family Drug Discovery Center, Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida, United States
  • Chen, Pingping, University of Miami Batchelor Children's Research Institute, Miami, Florida, United States
  • Merscher, Sandra M., Peggy and Harold Katz Family Drug Discovery Center, Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida, United States
  • Fornoni, Alessia, Peggy and Harold Katz Family Drug Discovery Center, Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida, United States
Background

Premature birth and low birthweight, prevalent in around 11% of pregnancies and disproportionately affecting Black Americans, amplify the long-term risk of chronic kidney disease (CKD). Neonatal hyperoxia leads to impaired development of the renal tubules, renal corpuscle enlargement, tubular necrosis, interstitial inflammation, and fibrosis. Furthermore, global kidney health is a mounting concern with CKD affecting both children and adults. Emerging evidence links Chaperone-Mediated Autophagy (CMA) to the degradation of oxidized proteins within cells, a process intensified during oxidative stress through mechanisms involving substrate protein modifications and transcriptional up-regulation of the Lysosome-associated membrane glycoprotein 2 (LAMP2A) at the lysosome. We hypothesize that in neonate, hyperoxia-induced oxidative stress triggers adaptive increases in CMA, which although protective initially, may lead to impaired CMA activity over time due to persistent oxidative conditions.

Methods

Sprague Dawley rat pups were reared in hyperoxic (HYP) with FiO2 of 0.85 or normoxic (RA) conditions until 10 days of life. Urine was sent for Urine Protein and Creatinine levels. Western blot and immunofluorescence were performed on kidney cortices. Immortalized human podocytes were cultured and exposed to hyperoxia or normoxia for 48 hours. Bulk RNA Sequencing analysis was conducted on rat kidney cortices and human podocytes.

Results

Urinalysis of hyperoxia-exposed rats revealed worsened proteinuria (Urine protein 132 mg/dl vs 20 mg/dl) and higher Urine protein/Creatinine ratio (14.2 vs 4.2). Western blot analysis of protein lysates from rat kidney cortices reveals a reduction in p62 expression in HYP rats with an increase in LC3 II/I ratio in HYP rats when compared to RA animals indicating an activation of autophagy. RNA sequencing results reveal decreased podocyte expression of circadian clock -controlled autophagy markers in bone metabolism including BHLHE41, CHRD, MAP1LC3A and TGFB1.

Conclusion

Taken together, these results indicate a role for altered circadian clock-mediated autophagy in hyperoxia-exposed podocytes affecting renal function.

Funding

  • Other NIH Support